A temperature of an internal combustion engine of a vehicle becomes high as the vehicle runs, and in general, the heated engine is cooled by a air cooling method or water cooling method. The air cooling method allows the engine to be contacted with atmosphere without additional supplement and prevents freezing and leakage of cooling water, and so on. However, cooling efficiency is low when temperature of outside air is high or the vehicle temporarily stops.
Thus, many vehicles apply the water cooling method that cools the engine by using cooling water. In the water cooling method, a water jacket is installed around a cylinder of the engine to cool the engine by circulating the cooling water stored in a radiator. Furthermore, in order to improve a cooling efficiency of the engine, a cooling fan for cooling the cooling water is provided at the radiator.
The cooling fan can be a single fan and a dual fan in accordance with the number of a motor. The single fan carries out the cooling using only a single motor, thus decreasing production cost. FIGS. 1A and 1B are views illustrating a shape of a single fan according to the prior art. Referring to FIGS. 1A and 1B, the single fan includes a motor for generating a rotating power and blades being rotated by the motor to generate air flow. Furthermore, the single fan includes a shroud fixing the motor and the blades and preventing the air generated by the blades from flowing backward. A resister is attached to one side of the shroud and controls a motor speed.
The resister radiates heat energy converted from a current induced to the motor and provides only the necessary amount of current to the motor, thereby lowering the motor speed. In this case, the radiated heat energy is not usable, and thus, the energy efficiency thereof decreases. Further, the temperature of the resister was risen up to the maximum 555° C., thereby fire risk of vehicles increases due to excessive heat of the resister.